Automatic storage and retrieval systems are used in warehouses or other facilities in which objects are to be temporarily stored. A known storage and retrieval system includes a storage rack defining storage compartments or locations, and a storage and retrieval machine (SRM) operable to deposit objects in designated storage locations on the storage rack and to retrieve those objects when desired. The storage and retrieval machine includes a base that is supported on wheels for rolling movement along a track, and an onboard motor drivingly connected to at least one of the wheels to move the storage and retrieval machine along the track. The base supports a vertically extending mast on which a carriage is supported for vertical movement. The carriage is typically supported for movement along the mast by wheels or rollers. The carriage supports an extractor or shuttle mechanism that is horizontally extendable beneath an object so that the object can be lifted from or lowered onto the storage rack.